#pragma once
#include <iostream>
#include <memory>

class Stock 
{
public:
  Stock() = default;
  ~Stock() = default;
  void buy();
  void sell();
};

using StockPtr = std::shared_ptr<Stock>;

void Stock::buy() {
  std::cout << "买股票！" << std::endl;
}

void Stock::sell() {
  std::cout << "卖股票！" << std::endl;
}